/* 返回按钮：从哪来回哪去 */
(function() {
var backBtn = document.getElementById('backBtn');
if (backBtn) {
var params = new URLSearchParams(window.location.search);
var referer = params.get('referer');
if (referer) {
backBtn.href = referer;
} else if (document.referrer && document.referrer.indexOf(window.location.hostname) !== -1) {
backBtn.href = document.referrer;
} else {
backBtn.href = 'index.html';
}
}
})();